Application of a Scale-Aware Gravity Wave Drag Scheme in High-Resolution Numerical Weather Prediction
As the resolution of numerical prediction systems increases,the subgrid-scale orographic gravity wave drag(GWD)and low-level blocking parameterization become less suitable.To address this issue,WRFv4.3 has introduced two additional orographic drag suites:small-scale GWD and turbulent orographic form drag,thus evolving into a scale-aware scheme.To evaluate the performance of this high-resolution model,application tests were conducted over North China.Three schemes were designed:a model with GWD shut down,a model with the original GWD activated,and a model with the new scale-aware GWD activated.The results reveal that the original GWD,which contains only subgrid-scale orographic GWD and low-level blocking without varying resolution,significantly affects wind at all levels in the model;however,the effect is not always positive.In contrast,the scale-aware GWD scheme minimizes the aforementioned factors to zero while maintaining small-scale GWD and turbulent orographic drag in the 3-km model.Therefore,the drag force exists only in the planetary boundary layer,and the low-level wind can be effectively improved.Statistical results show that the scale-aware GWD scheme can significantly decrease the positive bias and root mean square error of near-surface wind forecasts.However,for other variables,the improvement was not significant.
万方数据
维普
